Troubleshooting a KAP100 I/O failure
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Troubleshooting a KAP100 I/O failure
 
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I had (have) a problem, and my intent in this post is to add an article to the archive so that if some other fool makes the same mistake it may save them some time in the troubleshooting process.
Description of the problem: The KPA100 and KAT100 are remote in an EC2. After working on the K2, I buttoned up the case, connected my control cable, and on start the KPA100 failed. Most of the time the PA was not recognized, but once in a great while it would be recognized briefly. When that happened no PA functions were available in the secondary menu, and after reducing power to below 11 watts the PA ceased to be recognized, nor did K1 switch. However, the KAT100 was operational. Troubleshooting: Performing the resistance measurments at U1 indicated a short at pin 1, the 5v line. Assuming U3 had failed I removed it from the circuit. The short remained after the removal of U3. C25 tested fine as did C89. That left two suspects, U4 the MAX1406 and U6 the EL5146C. OK, a 50/50 shot so I removed the MAX1406 and the short still remained at pin 1 of U1. After pulling the EL5146CN the short disappeared. Lacking those chips I installed a new 78L05, and suddenly the KPA100 was recognized by the K2, and going from QRP to QRO K1 switched as expected, and passing through the bands all the low pass relays were operational. Now I wait for the mailman to bring me replacement MAX1406 and EL5146 chips. The cause: When U6 failed it shorted the 5v line disabling the MCU, it wasn't quite a dead short, showing about 13 ohms of resistance. Thus once in a blue moon it would be recognized on power up. So what happened that could cause this? In my haste to button up the K2 which has a KIO2 and KAT2 installed in the lid I didn't get the KIO2 cable on P4 on the control board aligned right. As a result of shifting the pins one row up I applied 12 volts to the RFDET line in the KPA100 causing failure of U6. It isn't used in the KAT100 so it was spared. The moral: Key the plug on the control cable of the KIO2 so you might avoid the pain and shame I experienced. Regards, Joe N9JR _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Troubleshooting a KAP100 I/O failure
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Joe and all,
I might add that one does not have to have a 'proper' keying plug in hand to do the job - a sliver cut from a toothpick will work, or since one should not be plugging and unplugging things with power on, even a tight fitting wire stuck into pin 4 will work fine. I have used both techniques. If you are inclined to use any sort of glue, resist the temptation, it will wick into places that it should not be and you will have to buy replacement connectors - a tight friction fit will work just fine. For those who do not have a KPA100, the 'keying' is applied to the 10 pin header on the K2 control board and any connectors that plug to it - cut off header pin 4 and insert a plug in the pin 4 position of the mating connector. After this is done, it is not possible to plug the connector the wrong way. You will have the connector present if you have installed either the KAT2 or the KIO2 or both. The KPA100 manual provides explicit instructions (and 2 insert plugs) to key the connection. 73, Don W3FPR > -----Original Message----- > > The moral: Key the plug on the control cable of the KIO2 so > you might avoid the pain and shame I experienced. > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Joseph Reed-2
Hi all,
My K2 #402 (KPA100/KAT100/KSP2) is just incredible. I can't believe my basic K2 is 6 or so years old, and never had a major problem with it. The more I use it the more dependable I think it is. Its not just that you can repair a K2 if it goes down, they just never seem to break or need adjustment. Anyway this rig has one quirk I really want to correct. I have done all the Elecraft recommended mods to this thing. I was a bit hesitant to do the audio mod since I previously had plenty of it, but did that mod and also replaced all of the pots (5) on the front panel. Well since the mod, and replacing all of the pots, the audio is very touchy near the almost off position about 8 o'clock. I have lived with it but noticed a few weeks ago that if I wiggled the audio pot the audio could be knocked down a lot, almost to an inaudible level. I also noticed at that time that I thought I might have had a grounding problem since when I went to adjust the keyer speed the volume would fluctuate. Well I played with it some more and it seems that whenever I "push" on the audio knob or the _keyer_ knob the volume goes way down. Yes the keyer knob affects my audio. I am thinking to take the front panel off (again) but might order a few pots again before I do. I can't believe the pots are bad. I wonder if I missed a solder connection. Any ideas? Also, on Sunday I made my first two RTTY contacts. That was really cool. I used MixW, and have the K2 filter buttons and a centering command on the menu. The RTTY mode really makes the filters work nice when you center the audio and DSP filters on your audio frequency. I still don't know what is the correct maximum output in the RTTY mode!!!! I have gotten conflicting advice. I am use a muffin fan on the heat sink. Steve, W2mY/5 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.5.1/326 - Release Date: 4/27/2006 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Steve,
Yes that does sound suspiciously like a missed or bad solder connection. Take the front panel apart and examine everything reflow the soldering if you can't locate it by inspection. Don't forget about the connectors - and the 'other side' of the connectors on the RF board as well - check the control board connectors while you are investigating too - these Front Panel signals mainly go to the Control Board by way of the RF Board. 73, Don W3FPR > -----Original Message----- > > Anyway this rig has one quirk I really want to correct. I have > done all the > Elecraft recommended mods to this thing. I was a bit hesitant to do the > audio mod since I previously had plenty of it, but did that mod and also > replaced all of the pots (5) on the front panel. > > Well since the mod, and replacing all of the pots, the audio is > very touchy > near the almost off position about 8 o'clock. I have lived with it but > noticed a few weeks ago that if I wiggled the audio pot the audio could be > knocked down a lot, almost to an inaudible level. I also noticed at that > time that I thought I might have had a grounding problem since when I went > to adjust the keyer speed the volume would fluctuate. > > Well I played with it some more and it seems that whenever I "push" on the > audio knob or the _keyer_ knob the volume goes way down. Yes the > keyer knob > affects my audio. I am thinking to take the front panel off (again) but > might order a few pots again before I do. I can't believe the > pots are bad. > I wonder if I missed a solder connection. Any ideas? > > Also, on Sunday I made my first two RTTY contacts. That was > really cool. I > used MixW, and have the K2 filter buttons and a centering command on the > menu. The RTTY mode really makes the filters work nice when you > center the > audio and DSP filters on your audio frequency. I still don't know what is > the correct maximum output in the RTTY mode!!!! I have gotten conflicting > advice. I am use a muffin fan on the heat sink. > > Steve, W2mY/5 > > -- > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.1.385 / Virus Database: 268.5.1/326 - Release Date: 4/27/2006 > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.385 / Virus Database: 268.5.1/326 - Release Date: 4/27/2006 > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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HI Don,
Thanks for the reply. OK, now the radio is perfect. I did decide to take it all apart once again, and I had checked everything except for the front side of the panel board. I do hate to put those knobs back on with the semi-stripped allen wrench holes. Anyway I did it, and was poking around and noted that the jumper that goes under the R4 pot really didn't look too good. I had used a piece of solid bus wire and some clear heat shrink tubing for insulation. I took it off and replaced it with a piece of 22 gauge stranded wire, the type you see at the front of the PCs for hooking up the idiot lights. This time I wrapped the wire over the top of R4 and R3. This way the minimum length possible of the wire is in a tight area. I put it all together and the thing works like a Rolls Royce. Now I've got the perfect radio. I am so happy with this rig. Its worth $12K to me. Thanks again, Steve, W2MY Corpus Christi PS: Apparently Corpus Christi, and one small part of the gulf coast in Florida were the only areas not touched, on the Gulf, by hurricanes last year. All the hospitals and EOCs down here suddenly are trying to put together ham radio stations as an alternate means of communication to satisfy FEMAs new requirements. I have been helping with spec'ing out equipment and am amazed at the high cost of halfway decent HF transceivers that don't come close to the K2's performance. Does anyone know of any EOCs out there that are using K2s for their HF needs? -----Original Message--------------------------------------------------------------------- ---------------------------------------------------------------------------- -- Yes that does sound suspiciously like a missed or bad solder connection. 73, Don W3FPR -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.5.1/326 - Release Date: 4/27/2006 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Troubleshooting a KAP100 I/O failure
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In reply to this post by Joseph Reed-2
Hi Jo,
Thanks for the very concise description of your problem, how you solved it and the cause. I think that you may have just stopped me becoming "some other fool".. I notice that there are no keys on any of the connectors associated with the KIO2 AUX2 Board. It looks like keys applied to all Pin 4's would be a good precautionary measure. We have been warned in the past about the dangers from without (standard RS232 cable vs Elecraft special), but not those lurking within. 73 Stewart G3RXQ Many thanks. On Fri, 28 Apr 2006 11:29:57 -0700 (PDT), Joseph Reed wrote: > I had (have) a problem, and my intent in this post is to add an article to > the archive so that if some other fool makes the same mistake it may save > them some time in the troubleshooting process. > > Description of the problem: The KPA100 and KAT100 are remote in an EC2. > After working on the K2, I buttoned up the case, connected my control cable, > and on start the KPA100 failed. Most of the time the PA was not recognized, > but once in a great while it would be recognized briefly. When that happened > no PA functions were available in the secondary menu, and after reducing > power to below 11 watts the PA ceased to be recognized, nor did K1 switch. > However, the KAT100 was operational. > > Troubleshooting: Performing the resistance measurments at U1 indicated a > short at pin 1, the 5v line. Assuming U3 had failed I removed it from the > circuit. The short remained after the removal of U3. C25 tested fine as did > C89. That left two suspects, U4 the MAX1406 and U6 the EL5146C. OK, a 50/50 > shot so I removed the MAX1406 and the short still remained at pin 1 of U1. > After pulling the EL5146CN the short disappeared. > > Lacking those chips I installed a new 78L05, and suddenly the KPA100 was > recognized by the K2, and going from QRP to QRO K1 switched as expected, and > passing through the bands all the low pass relays were operational. Now I > wait for the mailman to bring me replacement MAX1406 and EL5146 chips. > > The cause: When U6 failed it shorted the 5v line disabling the MCU, it > wasn't quite a dead short, showing about 13 ohms of resistance. Thus once in > a blue moon it would be recognized on power up. So what happened that could > cause this? In my haste to button up the K2 which has a KIO2 and KAT2 > installed in the lid I didn't get the KIO2 cable on P4 on the control board > aligned right. As a result of shifting the pins one row up I applied 12 > volts to the RFDET line in the KPA100 causing failure of U6. It isn't used > in the KAT100 so it was spared. > > The moral: Key the plug on the control cable of the KIO2 so you might avoid > the pain and shame I experienced. > > Regards, > Joe N9JR > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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